Adjustable bumper attachment for chain saws



P 1, 1951 A. w. MALL ETAL ADJUSTABLE BUMPER ATTACHMENT FOR CHAIN s Aws 2 Shee ts-Sheet 1 Filed Sept. 18, 1944 I VEIVTDNS #MK 5 01M X12 67: n TTO/Pnsy P 51 A. w. MALL ET AL v 7,

ADJUSTABLE BUMPER ATTACHMENT FOR CHAIN SAWS Filed Sept. '18, 1944 v 2 Sheets-Sheet 2 Patented Sept. 11, 1951 ADJUSTABLE BUMPER ATTACHMENT FOR CHAIN SAWS Arthur. W. Mall, Flossmoor, and Walter L. Gordon, Chicago, 111., assignors to Mall Tool Company, Chicago, 111., a corporation of Illinois Application September 18, 1944, Serial No. 554,679

1 Claim. 1 Our invention relates to chain saw machine and has as its general object the provision of an improved chain saw machine.

One Object of our invention is to provide improved, yet simple, chain tension adjusting means. Another object is to provide means for quickly removing the idler casting from the end of the chain guiding member to permit the chain guiding member and cutting chain to be pulled through'a kerf being out.

A further object is to provide a removable auxiliary bumper bracket to assist in limbing operations.

Further objects and advantages of our invention will be apparent upon reading the specification and upon examination of the drawings in which:

Fig. 1 is a perspective view of our chain saw machine showing the auxiliary bumper as used in limbing operations;

Fig. 2 is a side elevation of our chain saw machine showing the auxiliary bumper from the underneath side;

Fig. 3 is a fragmentary view of the auxiliary bumperbracket taken on line 33 of Fig. 2;

Fig. 4 is a fragmentary sectional view of the auxiliary bumper bracket taken on line 4-4 of Fig. 3;

Fig. 5 is a top view of the auxiliary bumper bracket alone;

Fig. 6 is a side elevation showing partially in section the idler sprocket assembly and chain tension adjusting means at the end of the chain guiding member opposite the power unit; and

Fig. '7 is a sectional view taken on line |-'I of Fig. 6.

It has been customary in the prior art to provide chain saw machines with bumper guards which are permanently secured to the power unit, against which guards the log being cut rests during the cutting operation. The diameter of a log which a chain saw machine is capable of cutting is determined by the span between this bumper guard and the guard on the opposite end of the chain guiding member. It is desirable to have the bumper guards at each end of the chain saw machine spaced as far apart as possible so that the chain saw machine will be capable of cutting as large a diameter log as possible. However, when the bumper guard is secured to the power unit, frequentlythe power unit hinders certain types of cutting operations, particularly limbing.

Referring to Figs. 1 and 2, we have shown our chain saw machine which is comprised generally of a power unit A, a chain guiding member B, a driving sprocket C and a cutting chain D.

. In our chain saw machine we obtain maximum diametric cutting capacity by forming the permanent bumper guard I integral with the power unit. When cutting a tree or log, the cutting chain D travels in the direction indicated in Fig. 2, consequently when the cutting chain engages the log or tree, it pulls the entire chain saw machine in a direction in which the power unit A is pulled against the tree. The bumper guard l is therefore continuously urged against the outer sur face of the tree while the cutting chain is progressing through the tree. The arcuate surface 2 of the bumper guard l prevents pinching while the cutting chain is progressing through the tree.

When it is desired to cut the branches from a tree which has been felled, it is frequently necessary to insert the cutting chain underneath the fallen tree. In cutting these underneath branches. it is necessary that the power unit be spaced away from the tree so as not to become jammed beneath the tree. We have thus provided an auxiliary bumper guard 3, which may be quickly attached and removed from the chain guiding member when it is desired to cut branches from a tree. We have provided a number of holes 4, in the chain guiding member B, which holes may be spaced at an equal distance from each other so that the bumper guard 3 may be attached in any of several positions along the guiding member. v

The bumper guard 3 consists of a casting having arcuately shaped front surfaces 5 and 6 and a central portion 1 which provides a bearing surface for the guiding member B. It will be noted that the bearing surface I protrudes outwardly and away from the underneath surface 8 of the bumper guard, thereby providing clearance space between the face 9 of the chain guide member B and the underneath surface 8 of the bumper guard 3. The reason for this is to permit the cutting chain D to travel around the guide member B past the bumper guard 3 without scraping against the underneath surface 8 of the bumper guard. The bumper guard is provided with a pair of bosses l0 and II through which a pair of bolts l2 and I3 extend, These bolts are inserted through the bosses by pressed fit so as to be rigid therewith and non-rotatable therein. The bolt It extends beyond the underneath surface of bearing portion 1 just sufiiciently far so as to extend into the hole 4 in guide member B, but not all the Way through said hole. Bolt I'Z merely serves to locate the bumper guard 3 in correct position and in cooperation with bolt l3 prevents the bumper guard from rotating relative to guide member B. Bolt I3 extend through hole 4 and has a threaded portion protruding to the other side of the guide member. Wing nut M- removably secures the bumper guard 3 to the guide member B. It can be seen that the bumper guard The main casting i6 is provided with a web portion ll which extends transversely across the casting. Formed integral with the web portion I? is a downwardly depending wall portion l8 and The wall por-.

elongated slot 2! in the end of the chain guide member B. On either side of the lug member the wall portion 19 provides flat bearing surfaces for chain guide member B to rest against. It will be noted that the plane defined by the lower surface of the lug member 29 is slightly above the plane defined by the outer surface 22 of guide member B, the reason for which will be hereinafter described. Wall portion l9 has an internally threaded boss 23 which receives the threaded end of bolt 24. Bolt 24 has a rectangularly shaped head portion 25 with a fiat under- B securing said guide member B to casting 16. It is significantto note that the thread on bolt 24 are coarse so that the bolt moves inwardly rapidly and whenthe head portion 25 is parallel lengthwise with slot 2!, the side walls of head portion 25 do not sink into slot 2| just prior to the time that head portion 24 becomes tightened against guide member B. The width of head portion 25 is slightly less than the span of slot 2!, consequently, when bolt 24 is loosened the head portion 24 may be pushed downwardly through the slot 2! when it reaches lengthwise alignment with said slot. When head portion 24 is pushed through slot 21 beyond the opposite face of guide member B the casting It may be pushed forwardly relative to guide member B and then the cutting chain drops away from sprocket 28. Then the guide member and cutting chain can be withdrawn through the kerf of the 'log being outwith nothing to obstruct its withdrawal. l K I Guard bar 29 may be sprung outwardly away from bolt 39 when'pushing'casting I6 forwardly relative to guide member B. The wall portion i 8 4 chain when the machine is in felling position as shown in Fig. 6.

In order to accomplish adjustment of chain tension, we have provided handle 42 which is rotatably received in the outer end of casting H3 by means of shaft portion 43. A thrust washer 44. is interposed between the handle 42 and the end of casting IE to provide additional wearing life. 'A "rod'45' extends through handle 42 and, is keyed thereto by means of a pin 46 so as to be rotatable along with handle 42.

A compression spring 41 normally urges the handle 42 against casting l6 maintaining handle 42 and casting l6 together as a unit. Rod 45 screw-threadedly engages sprocket carrier 48 for effecting adjustment of said sprocket carrier toward and away from guide member B, thereby varying the tension on the cutting chain D. When it is desired to change the adjustment of the tension of the cutting chain, pin 49 is pulled outwardly against the tension of compression spring 50 thereby withdrawing the fiat end portion 5i of pin 49 out of a slot 52 in the shaft portion 43 of handle 42. When pin 49 is retracted, handle 42 can be rotated to effect adjustment of chain tension and then pin 49 is released and end por- 1 tion 5i drops into a slot 52 to prevent further neath surface for bear ng aga nst guide member rotation of handle 42 thereby maintaining the adjusted chain tension. When retracting pin if it should be desired to maintain saidpin in retracted position, this can be accomplished by rotating the pin 49 until stop pin 53 rests on the upper end of boss 54. Then pin 49 is released by rotating until stop pin 53 drops into slot 58.

Having thus described our invention, what we claim is:

A chain saw machinecomprising a power unit, a. guide member extending outwardly from the power unit, a cutting chain having. driving engagement with the power unit and being trained about the guide member, the guide member being provided with a plurality. of perforations spaced in linear. relationship from the power unit, a bumper member spaced from the power unit and being adapted to be selectively located over the perforations, and means cooperating with the in casting I6 is of suff cient thickness to accomthe oil for the cutting chain is introduced. The upper ends of "these passageshave enlarged regions 34 and 35 which serve" as reservoirs to hold a quantity of oil for a limited amount of time. The lower ends of the passages 39 and3i have restricted regions 36 and 3 which open into the outer surface of wall portion til at 38 and 39 These restricted regions permit only a limited amount of oil to drop onto the chainoccasionally. It will be noted that passage 30 extends through casting I6 in a diagonal direction whereas passage 3| extends through casting it, perpendicularly to the plane of the cutting. chain. This permits oilingthe cutting chain in its two normal cutting positions; felling and bucking. Referring to Fig. 7, we have shown our machine in bucking position- Passage 3.0 is. used to oil the cutting chain when in bucking position and passage 3| is used for oiling the cutting selected perforations for securing the bumper member in place on the guide member.

. ARTHUR W. MALL.

WALTER L. GORDEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Date I Name 828,436 Stewart Aug; 14, 1906- l,195,945 Mitchell et a1 Aug. 22, 1916 1,410,198 Lofgren Mar. 21, 1922 1,617,565 Bens Feb. 15, 1927 1,753,959 Wickstrorn Apr. 8-, 1930 1,802,129 Vaccari Apr. 21, 1931 1,861,162 Quist May 21, 1932 1,903,571 Meyer Apr. 11, 1933 2,046,231 Alexander June 30, 1936 2,165,524 Wolf July 11, 1939 2,296,240 Blum Sept. 22, 1942 2,327,233 Wolf Aug. 17, 1943 p FOREIGN PATENTS Number. Country 2 Date 274,348. Great Britain July21. 1927 115,178 Australia May 18', 1942 

